In this paper, we consider some hybrid Diophantine equations of addition and multiplication.
First of all,
n = x1 + x2 + ··· + xs
such that
x1x2 ··· xs = xk,
for n, xi, x, k ∈ Z+, which is a new variant of Waring’s problem:
n = xk
1 + xk
2 + ··· + xk
s .
We denote by g
(k) (resp. G
(k)) the least positive integer such that every integer (resp.
all sufficiently large integer) can be represented as a sum of at most g
(k) (resp. G
(k))
positive integers, and the product of the g
(k) (resp. G
(k)) integers is a k-th power. We
show [2] that
g
(k)=2k − 1; G
(p) ≤ p + 1;
G
(2p) ≤ 2p +2 (p ≥ 3); G
(4p) ≤ 4p +2 (p ≥ 7);
where k is a positive integer and p is prime. In this paper, we improve the results on
composite numbers as follows.
Theorem